Question

Which statement regarding isocitrate dehydrogenase is false?

a. It catalyzes a reversible reaction under physiological conditions.
b. It catalyzes an oxidative decarboxylation.
c. In eukaryotes, there is an NAD+‑dependent form found in mitochondria and an NADP+‑dependent form found in both mitochondria and the cytosol.
d. It has a Mn2+ cofactor.

Answer 1

a. It catalyzes a reversible reaction under physiological conditions.

Step-by-step explanation:

Option (a) is false.

Isocitrate dehydrogenase catalyzes the conversion of isocitrate into α-ketoglutarate through oxidative decarboxylation and this reaction is irreversible not reversible. The reason behind irreversibility of this reaction is large negative Gibb's free energy change which occurs during this reaction and makes this reaction feasible.

Rest of the options are correct because Mn²⁺ is used as a cofactor during this reaction. Also two forms of this enzyme exist in eukaryotes, in mitochondria we can find NAD⁺ dependent form while NADP⁺ dependent form is found in mitochondria as well as cytosol.